We demonstrate coexistence of slow and fast components of photoluminescence decay of the Mn²⁺ intra-shell emission in nanoparticles of CdMnS. We explain the observed decrease in PL lifetime of the Mn²⁺ intra-shell transition by high efficiency of spin dependent magnetic interactions between localized spins of Mn²⁺ ions and free carriers. This mechanism is enhanced in nanostructures, but it is also present in bulk samples.